[INTERNAL] TreeTable: Fix JSDoc of setUseFlatMode function
[INTERNAL] TreeTable: Fix JSDoc of setUseFlatMode function

Change-Id: I8b7bcea1d950912b4f74f9b5f430752db86a91de

cschuff/openui5,nzamani/openui5,SQCLabs/openui5,SAP/openui5,SQCLabs/openui5,SQCLabs/openui5,SAP/openui5,cschuff/openui5,SAP/openui5,nzamani/openui5,nzamani/openui5,cschuff/openui5,SAP/openui5